通过ajax从jsp页面传输数据到web层，并从web层返回数据给jsp页面

jsp中ajax代码：
 1            $.ajax({
              var id = $("#studentid").val();//获取标签中的学生id
              url:'${pageContext.request.contextPath}/student/stu_delStudent.action?studentid='+id,
              data:'',
              type:'POST',
              dataType:'json',
              async:false,
              success:function(data){
                  alert(data.message);
              }
              
          }); 

action中的代码：
1 public class StudentAction extends ActionSupport{
    private Student student;
    public Student getStudent() {
        return student;
    }
    public void setStudent(Student student) {
        this.student = student;
    }

    @Resource
    private StudentService studentService;
    
    public String delStudent() throws Exception{
        //接收请求数据
        int studentid = ServletActionContext.getRequest().getParameter("studentid");
        studentSerivce.delByStudentId(studentid);
        //创建一个JSON对象
        JSONObject json = new JSONObject();
        json.put(“message",删除成功");//将返回信息保存在JSON对象中
        HttpServletResponse response = ServletActionContext.getResponse();
        //设置响应编码格式，防止乱码
        response.setContentType("text/html;charset=UTF-8");
        //将数据以json格式响应给ajax
        response.getWriter().write(json.toString());
        
        return null;
    }
}